Annotation is an important feature in many printers, facsimile machines and multifunctional devices. Conventional devices, typically offer two modes of annotation: opaque and transparent annotating.
In the opaque mode, typically a white box with annotating text replaces the area to be annotated. On the other hand, in transparent mode, the annotating text is superimposed on the original image. Conventionally, the transparency mode has been used for bi-level (or binary image data). This may be performed, for instance, using an “OR” logic operation between the original pixel values and the corresponding annotating text values in the specified area.
The transparency mode using the OR logic operation, however, does not extend naturally to multi-level image data, or for color image data.